1. Field of the Invention
The present invention relates to apparatus for driving tools and in particular relates to pneumatically driven tools for use in combination with other machine tools.
2. Description of the Prior Art
Many machine tool applications, particularly production applications, require a variety of special tooling packages specifically designed for one type of application. Often this requires production of custom tooling to suit a specific customer's needs. For example, pneumatic valve grinders such as shown by Kelly, "Valve Grinder", U.S. Pat. No. 2,614,372, or pneumatic crank pin grinders such as shown by Prill, "Crank Pin Grinder", U.S. Pat. No. 2,257,619, typify apparatus which are not only specifically designed for a particular type of grinding or tooling application, but are also customized to a specific model valve seat or crank pin.
Other pneumatic grinders are also well known in the art where the grinder serves as a fixed machine head or as a general-purpose hand-held tool, such as used for polishing as shown by Birkenstock, "Pneumatic Polishing Tool", U.S. Pat. No. 691,740, Kakimoto, "Pneumatically Driven Grinder", U.S. Pat. No. 3,885,335, or Kakimoto, "Small Diameter Cylindrical Air Motor for Driving Grinders and the Like", U.S. Pat. No. 3,827,834. However, when applied in combination with standard lathes or milling machines, such independently driven grinding apparatus have typically been mechanically powered by gear trains or belts and pulleys by the same machinery used to power the lathe. An example of this prior art practice is shown by Blood, "Grinding Machine", U.S. Pat. No. 1,970,645, and by Fletcher, "Pneumatic Tool", U.S. Pat. No. 833,710.
Even in those cases where a pneumatically driven tool is combined with a standard engine lathe its use has been limited and restricted by the limitations imposed upon the tooling by the fixed mechanical coupling, usually through a drive shaft, between the pneumatic motor and the grinding wheel, see, for example, Rhinevault, "Grinding Machine", U.S. Pat. No. 1,236,604.
What is needed is some means of configuring a pneumatically driven tool so that it can be treated as a universal tool used in combination with standardized, quick-change tool holders in conventional milling machines or lathes. In addition, some means is needed to conveniently select both the position and the orientation of the pneumatically driven tool with respect to the workpiece without having a customized tool for each position or oeientation. In addition, a means is needed whereby the operating speed of the grinding wheel coupled to the pneumatically driven motor wheel can be varied or changed, again without having a completely separate tool for each application.
These and other objects of the present invention can be best understood by considering the following brief summary of the invention.